From some research, I think I need the kernel-headers package. Gslapt shows that kernel-headers is installed, but it's for 2.6.38.3, not the 2.6.38.7 that's currently in VL 7.0 RC2. Does that matter? If so, where do I get the newer version, and if not, what else might be wrong?

(I put this in Hardware & Drivers since it's not really a "bug report")

building drivers in the live version will not work there is no kernel source due to size constraints. If everything else works suggest you should install the full STD release and you should be able to build any driver you need. The live CD is meant for demo purposes and because of size contraints even installing it to your hd will leave a lot missing versus the STD install.